Southern green stink bug

Nezara viridula

Profile

The Southern green stink bug is a bug that mainly attacks pulses, but also numerous vegetable, fruit and arable crops as well as ornamental trees and plants. It causes sucking damage, resulting in spotting, corking and deformation.

Appearance

The Southern green stink bug belongs to the family of tree bugs and is approx. 14-16 mm long, 8 mm wide and usually green in colour, although there are also specimens with a white head and front edge of the pronotum. In autumn it changes colour from green to reddish brown. The young bugs (nymphs) are very differently coloured and change their appearance with each stage of development. Newly hatched bugs are bright orange and then change colour to reddish brown. As they continue to develop, they become black in colour with white spots. Towards the end of their development into adult bugs, the green part usually predominates, with the lateral edges and the centre of the abdomen showing red and yellow dots.

frisch geschlüpfte orange Wanzen der grünen Reiswanze auf weißem leerem Eigelege
Erstes Larvenstadium auf leerem Eigelege
Grüne Reiswanze im zweiten Larvenstadium mit schwarzer Färbung und weißen Punkten
Zweites Larvenstadium der Grünen Reiswanze
Grüne Reiswanze im dritten Larvenstadium mit schwarzer Färbung und weißen Punkten
Drittes Larvenstadium der Grünen Reiswanze
Grüne Reiswanze im vierten Larvenstadium mit schwarzer Färbung und weißen Punkten
Viertes Larvenstadium der Grünen Reiswanze
Grüne Reiswanze im fünften Larvenstadium mit grüner Färbung und weißen Punkten
Fünftes Larvenstadium der Grünen Reiswanze
Sojabohnenpflanze mit mehreren Grünen Reiswanzen in unterschiedlichen Entwicklungsstadien
Unterschiedliche Entwicklungsstadien der Grünen Reiswanze in einem Sojabohnenfeld
Sojabohnenpflanze mit dicht gedrängten Nymphen der Grünen Reiswanzen
Massenhafte Ansammlung von Nymphen der Grünen Reiswanze an Sojabohne
Grüne Reiswanze auf einem Blatt
Grüne Reiswanze
Grüne Reiswanze mit weißem Kopf und Halsschild
Grüne Reiswanze mit weißer Färbung
Grüne Reiswanze mit rotbrauner Färbung
Grüne Reiswanze mit rotbrauner Färbung

Possibility of confusion

The Southern green stink bug looks very similar to the green stink bug(Palomena prasina), but the green rice bug can be easily distinguished from the green stink bug by the white row of dots on the front edge of the dorsal shield and the light-coloured transparent part of the elytra.

Biology

When the temperatures rise in spring, the adult bugs leave their overwintering quarters (e.g. ground litter, buildings) to start feeding. In April/May, the bugs mate and the females lay their first cream-coloured and later orange-coloured egg clutches, which contain up to one hundred individual eggs. The larvae that hatch from these eggs go through five very variably coloured stages, which are usually found in groups on the plants. In Austria, depending on the temperature in early summer, their development is completed after around two months and the first adult bugs of the first generation emerge, which start laying eggs again in June/July. From this, the second generation of rice bugs develops, which usually appears very conspicuously in late summer. A strong increase in the number of bugs can be observed in years with hot and dry summer conditions.

Damage symptoms

The Southern green stink bug can cause sucking damage to all above-ground plant parts. As a plant sucker, it is able to pierce plant tissue from young shoots, fruits, seeds, leaves and shoots with its proboscis in order to feed on the plant sap. Phytopathogenic viruses are not transmitted to the plants, but the sucking activity causes spotting, corking, deformation and death. Fruits become unsightly, can fall off prematurely and are no longer marketable.

In addition, flavour impairment is caused by the secretion of an unpleasant smelling secretion and the puncture sites can serve as entry points for pathogens.

An infestation by the green rice bug therefore has a qualitative and quantitative effect on the yield.

Host plants

The Southern green stink bug can feed on a wide variety of plant species from all crops. Its main host plants include legumes (e.g. soya, beans), but also vegetables (e.g. tomatoes, melanzani, peppers), fruit, wine and berries (e.g. apple, raspberry), as well as arable crops (maize, potato), herbs, ornamental shrubs and plants, various weeds and intercrops. Annual, herbaceous crops in particular are attacked especially at the time of fruit and seed formation.

Distribution

In Europe, the Southern green stink bug was initially only found in the Mediterranean region. Due to global warming, however, it is increasingly spreading northwards. Until 2015, only individual animals were found in Austria. In the meantime, the Southern green stink bug is considered established, as numerous larvae and adult bugs have since been detected in home gardens and glasshouses, especially in urban regions (Vienna and Graz).

In 2021, we were able to determine in a monitoring programme that the bug causes damage to gardens and agriculture, especially in late summer in Vienna and Graz, but also in Lower Austria and Burgenland. The Southern green stink bug has also already caused damage to vegetables in protected cultivation. In greenhouse crops, the bug becomes active as early as January or February, as it can survive the winter in a dormant stage in structural parts of heated glasshouses. Due to the fact that the green rice bug has developed into a significant pest in recent years, a warning service has been carried out together with the Chamber of Agriculture since 2023 to inform farmers about the current occurrence of the bug. Thanks to the numerous reports we received in the course of rice bug monitoring in 2023, we were able to create a distribution map for Austria.

Prevention and control

  • Regular plant inspections to recognise infested individual plants as early as possible and to remove egg layers/larvae/adults by collecting them. A jam jar is best suited for this, which should then be kept in the freezer for a few hours to gently kill the bugs.
  • To prevent the bugs from flying into the greenhouse, close-meshed (1-1.5 mm) insect screens can be fitted to the vents.
  • Check greenhouses for bugs before planting susceptible crops.
  • Direct control with authorised insecticides against sucking insects is possible, but difficult because it is usually not possible to achieve a sufficient effect against the adult bugs.
  • Egg parasitoids (ichneumon wasp Trissolcus basalis) and endoparasites (caterpillar fly Trichopoda pictipennis) are described as natural antagonists. According to the plant protection product register, the ichneumon wasp Trissolcus basalis has been authorised and commercially available in Austria since January 2023 for various crops in vegetable, fruit and ornamental plant cultivation, both outdoors and under glass.

Online registration platform

In cooperation with the chambers of agriculture, we carry out Austria-wide monitoring in legumes and other agricultural crops. This monitoring has recently been supplemented by an online reporting platform: Southern green stink bug reports | warning service - vegetables.

This year, only farmers and advisors can report findings of the green rice bug, stating the date and location of the discovery, the crops affected and the level of infestation. We want to use this data to obtain more information about the infestation situation in agriculture in Austria.

Links

First detection of the egg parasite Trissolcus basalis in Austria

Information from the CABI invasive species compendium: Datasheet Nezara viridula

Information from LTZ Augustenberg

Last updated: 12.02.2024

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